1. Field of the Invention
The invention relates to the field of devices for binding a shoe or boot to a sports article and, more particularly, the invention relates to the types of bindings that the heel of the boot to be raised with respect to the sports article.
Binding devices of the aforementioned type are used, for example, in cross-country skiing, ski touring, Telemark skiing, snowshoeing, ice skating, and roller skating.
2. Description of Background and Relevant Information
Binding devices are known in the sport of cross-country skiing, in which the front of the boot has a journal pin that is received in a jaw of the binding. The boot then describes a mere rotational movement with respect to the ski to which it is coupled These types of devices generally have a fixed elastic buffer against which the front end of the boot is compressed when the heel is raised, so as to push the boot back to a lowered position. Such a system is described, for example, in French Patent Publication No. 2 650 192 and in U.S. Pat. No. 5,152,546.
Other systems have been proposed in which the boot has a second zone for connecting to the binding, in addition to the first front articulation zone. This second zone is generally connected to a system for the elastic return of the boot. French Patent Publication No. 2 739 788 and U.S. Pat. No. 6,017,650 disclose a device in which a connecting rod having a fixed length is articulated on the second zone for connecting the boot (in this case a pin/axis), on the one hand, and on a sliding carriage that compresses a return spring, on the other hand. In the European Patent Publication No. 1 106 218 and U.S. Patent Application Publication No. 2001/0002747, the connecting rod is articulated at two fixed points but has a variable length, here again to ensure a return function. In both cases, the connecting rod does not in any way affect the trajectory of the boot with respect to the connecting member, which trajectory is therefore an arc of a circle about the connecting zone located at the front of the boot.
French Patent Publication No. 2 727 060 discloses a binding device provided with a flexible connecting rod, one end of which is fixed, connected by nesting to the base of the binding, and the second end of which is connected to a pin arranged behind the front end of the boot. The front end of the boot has a longitudinal groove that cooperates with a complementary rib of the binding in order to cooperate in the transverse guiding of the boot with respect to the binding.
International Patent Publication No. WO 01/93963 and U.S. Patent Application Publication No. 2003/0168830 disclose a system having a connecting rod with a fixed length, which is connected at its two ends to the base of the binding and to a rear engagement element of the boot, respectively. The device has a second connecting rod that is connected to a sliding carriage of the base, on the one hand, and to a front engagement element, on the other hand. This system has the drawback of not providing good stability to the boot in torsion about a vertical axis. Indeed, during such a force (which is particularly present when performing a turning step or a skating step in cross-country skiing), the boot causes a displacement of the sliding carriage on which the second connecting rod is articulated. The return force of the spring that acts on the carriage is insufficient to enable the boot to be held efficiently in torsion. Furthermore, this system does not allow any retention of the front of the boot if the user loses his/her balance rearwardly, the front of the boot then being free to be raised.